Rose-scented geranium (Pelargonium graveolens L.) is a multi-harvest high value aromatic crop. Essential oil extracted through hydro-distillation of shoot biomass of geranium is used in fragrance, flavor and pharmaceutical industries. It is a vegetatively propagated (through rooted cutting) and initially slow growing. To utilize the crop resources, more efficiently and improve production potential a field experiment was conducted for two cropping years (2005-2006) in a temperate climate to evaluate the feasibility of intercropping of cabbage (Brassica oleracea L.var. capitata), cauliflower (Brassica oleracea L. var. botrytis), vegetable pea (Pisum sativum L.) and radish (Raphanus sativus L.) in rose-scented geranium. Plant canopy, leaf: stem ratio, biomass and oil yield of rose-scented geranium was significantly influenced by intercrops at first harvest while second harvest had no significant variation in plant height and canopy. Biomass and oil yield of rose-scented geranium was increased in all intercrops at the second harvest (after harvest of intercrops). Maximum biomass and oil yield was obtained in rose-scented geranium+vegetable pea (intercrop) treatment than sole rose-scented geranium. The resource use efficiency (LER, ATER and LUE %) and geranium oil equivalent yield (GEY) were higher in all intercrops treatments compared to sole. The study showed that C/G ratio in rose-scented geranium was also influenced by intercrops. The quality of geranium oil was good and readily accepted in the aroma industry.

Intercropping, the practices of growing more than one crop in a field at the
same time, was commonly used in the world. It continues to be widely used in
much of the developing world, where farmers have only limited access to the
agricultural equipment and products that transformed agriculture in the industrialized
world (Willey and Cynthia, 1981; Horwith,
1985). A recent agriculture practice which typically uses monocultures,
has increased yields enormously in the developed countries but the improvement
has not been without its costs. The production and operation of modern tools
and synthesis of fertilizers and insecticides cost an enormous amount of energy.
Other costs can be high as well, ranging from soil erosion, less resources utilization
efficiency, more weed competition and the cumulative effects of excess pesticides
and fertilizer use, alternative are being sought that could maintain or improve
yield potential and quality while minimizing negative environmental effects.
One of these alternatives is intercropping rose-scented geranium with vegetables
(Prakasa Rao et al., 1986). Intercropping with
vegetables could lead to better land use efficiency as an important component
of sustainable farming (Dhyani et al., 1995).

Rose-scented geranium and vegetables (cabbage (Brassica oleracea L. var. capitata), cauliflower (Brassica oleracea L. var. botrytis), vegetable pea (Pisum sativum L.) and radish (Raphanus sativus L.) can be grown during the winter season in the Himalayan region of India and they need proper management for their growth and yield. Vegetables take two to four months and rose-scented geranium five months to come to maturity for their first harvest and another four months for second harvest. The compatibility of these two crops as companion crops in an intrcropping system was not explored earlier.

The present investigation was initiated to evaluate the feasibility of growing a short duration vegetable crop during the initial lag phase of rose-scented geranium in such a way as not to affect the yield potential of (rose-scented geranium) intercropping systems.

MATERIALS AND METHODS

Experimental site: The field experiment was conducted during the two cropping years 2005-2006 and 2006-2007 at the experimental farm of the Central Institute of Medicinal and Aromatic Plants, Research Centre, Purara, Bageshwar, Uttrakhand, India. The location has a temperate climate. The study was laid out in a randomized complete block design with five treatments and four replications. The soil was a sandy loam with pH 6.6 (soil: water, 1:2.5), 0.43% organic carbon, 125 kg ha-1 available nitrogen, 9.6 kg ha-1 available P, 150 kg ha-1 exchangeable K. Treatments were: Sole crop of rose-scented geranium spaced at 60 cm between rows and 45 cm between plants and rose-scented geranium (60x45 cm) intercropped with cabbage (Brassica oleracea L. var. capitata cv. Diamond), Cauliflower (Brassica oleracea L. var. botrytis cv. Pusa Agahni), vegetable pea (Pisum sativum L cv. Arkel) and radish (Raphanus sativus L. cv. Pusa himani). In between two rows of planted rose-scented geranium one row of each of the vegetables was sown/planted. The number of plants/plot of rose-scented geranium was constant in all the treatments.

Field preparation and transplanting: Terminal stem cuttings of uniform size (9-10 cm length, 2-3 nodes and 2-3 terminal leaves) of rose-scented geranium cv. CIM-Pawan grown in polythene bags (10x16 cm diameter filled with native soil) were kept under partial shade and regularly watered. Healthy, profusely rooted, 60 days old cuttings and vegetables were planted in October and the first week of November in each cropping years 2005 and 2006, respectively. Crops were irrigated at 15 days intervals and kept weed free through frequent manual weeding. Each plot was 3x2 m and fertilized with 100 kg N (225 kg urea), 80 kg P (500 kg single super phosphate), 60 kg K2O (100 kg muriate of potash) ha-1 in each years. Intercrops received no extra fertilizers. Sowing, planting, harvesting, crop geometry and fertilizer application are given in Table 1.

Harvesting and yield advantage calculations: Rose-scented geranium was harvested twice each cropping year (first in March and second in June) and the herb was distilled in a field distillation unit operating on hydro-cum-steam distillation principle. The essential oil yield (kg ha-1) was calculated by multiplying the biomass yield by essential oil recovery from the distillation unit. Intercrops of radish, cabbage and cauliflower and vegetable pea were manually harvested in January, February and March, respectively.

To test the advantage of intercropping compared to monocropping, geranium oil
equivalent yield (kg ha-1), Land Equivalent Ratio (LER), Area Time
Equivalent Ratio (ATER) and Land Use Efficiency % (LUE %) were computed (Panda,
2005).

Geranium oil equivalent yield was calculated by multiplying yield with price of produce and divided by the price of geranium oil:

where, Yab is the total biomass yield (first harvest+second harvest) (t ha-1) of rose-scented geranium in intercropping; Yaa is the total biomass yield (first harvest + second harvest) (t ha-1) of rose-scented geranium in monocropping; Yba is the yield (t ha-1) of intercrops in intercropping and Ybb is the yield (t ha-1) of intercrops in monocropping:

where, ta is the duration of rose-scented geranium in days; tb is the duration of intercrops in days and t is the total duration of intercropping system in days.

By using LER and ATER values, the land utilization efficiency % (LUE %) was calculated:

Crop culture summery for rose-scented in geranium different
intercrops

*Fertilizer application N: P: K @ 100:80:60 in sole geranium
and intercrops, 1/3 N, Full P and K at planting, 1/3 N at last week of December
and 1/3 N after intercrop harvest

Hydrogen was the carrier gas at 1.0 mL min-1. Temperature programming
was done from 70°C-230°C at 4°C min-1 with initial and
final hold time of 2 min (for BP-20) and from 70°C- 250°C at 3°C
min-1 (for PE-5). Split ratio was 1: 30. The injector and detector
temperatures were 200°C and 230°C on BP-20 and 220°C and 300°C
on PE-5 column, respectively. The GC-MS analysis of the oils was carried out
on a Perkin-Elmer Turbomass Quadrupole Mass spectrometer fitted with PE-5 fused
silica capillary column (50 mx0.32 mm; 0.25 μm film coating). The column
temperature was programmed from 100 to 280°C at 3°C min-1,
using helium as carrier gas at a flow rate of 1 mL min-1. The injector
temperature was 220°C and MS conditions were: EI mode operating at 70 eV,
ion source temperature was 250°C. Identification of components was done
by comparing retention times of GC peak with those reference compounds run under
identical conditions; by comparison of retention indices with literature data
(Davis, 1990; Verma et al.,
2010) by peak enrichment on co-injection of authentic samples, by comparing
mass spectra of the peaks with MS Library search (NIST and Wiley). The peak
area percentage was computed from the peak areas without applying FID response
factor correction.

Statistical methods: Data were subjected to analysis of variance using the SPSS programme (version 13) as applicable to randomized block designs. Duncans multiple range tests was used to determine separate means.

RESULTS

Rose-scented geranium plant growth attributes: Intercropping of rose-scented geranium with cabbage, cauliflower, vegetable pea and radish had no significant effect on plant height at both harvest (first and second) as compared to sole crop in both year (Table 2). Plant height ranged from 48.5 to 52.2 cm in monocropping and geranium plus pea intercrop, respectively, amongst the all intercrops.

As leaves is the main source of oil in rose-scented geranium plant, the higher leaf: stem ratio is a desired component for oil yields. Intercrops significantly affected the leaf: stem ratio at the first harvest and ranged from 1.4 to 1.8 compared to 2.7 in the monocrop (Table 2). After the intercrops harvest reduce the plant height and increase the leaf stem ratio in all the treatments combination.

Plant spread (canopy) of rose- scented geranium in the first harvest was significantly reduced by intercropping with cabbage, cauliflower, vegetable pea and radish (Table 3). The average (two cropping year) decreases were: 5, 8, 27 and 25% in cabbage, cauliflower, vegetable pea and radish intercrop treatments, respectively. At the second harvest rose-scented geranium had no significant variation on plant spread with any intercrops over sole.

Table 2:

Plant height and leaf:stem ratio of rose-scented geranium
in different intercrops

Mean fallowed by the same letter within one column (Plant
height, Leaf Stem ratio) do not differ significantly at p = 0.05

Table 3:

Plant spread (cm) of rose -scented geranium in different
intercrops

Mean fallowed by the same letter within one column (Plant
canopy) do not differ significantly at p = 0.05

Table 4:

Variation in biomass yield (t ha-1) of rose-scented
geranium in different intercrops

Mean fallowed by the same letter within one column are not
differ significantly at p = 0.05

Rose-scented geranium yield attributes: Intercropping of rose-scented
geranium with cabbage, cauliflower, vegetables pea and radish led to significant
reduction in biomass and oil yield in both the cropping years in comparison
to sole crop in the first harvest (Table 4, 5).
At first harvest the biomass yield (mean of two cropping year) reductions were:
14, 17, 38, 23% and oil yield were: 11, 18, 32, 22% in the cabbage cauliflower,
vegetables pea and radish intercrop treatments, respectively, compared to sole
crop. At the second harvest rose-scented geranium plus vegetable pea had higher
biomass and oil yield.

Table 5:

Variation in essential oil yield (kg ha-1) of
rose-scented geranium in different intercrops

Values in a column fallowed by the same letter within one
column are not significantly different at p = 0.0

However, total biomass and oil yields of both cropping years (first harvest
plus second harvest) was significantly less 5, 8, 14 and 12% and 5, 7, 11 and
12% in cabbage, cauliflower, vegetables pea and radish respectively, over sole
crop of rose-scented geranium.

Intercrops yields: Intercrops yield varied in all intercropping systems of rose-scented geranium (Fig. 1). Yield variation of intercrops was 39.5, 37.7, 25 and 46.6% in cabbage, cauliflower, vegetable pea and radish, respectively over sole intercrops. Maximum reduction was obtained in radish followed by cabbage and cauliflower.

In first harvest, percentage of geraniol, nerol, geranyl acetate, neral (Z)-rose
oxide and α-pinene was higher in sole crop than intercropped. However,
its reverse was true for citronellol, isomenthone, geranial and citronellyl
acetate i.e., these constituents were increased by introducing intercrops in
rose-scented geranium. Similar to first harvest, the amount of geraniol (34.11%)
was also found to be higher in sole crop compared to intercropped with cauliflower
(23.64%) and reddish (31.79%) in second harvest, however, it was lesser than
that observed in rose-scented geranium intercropped with cabbage (35.07%) and
pea (36.09%.) in second harvest. Further, the percentage of citronellyl formate
(6.17%) and geranyl formate (4.23%) was higher in sole crop, while the amount
of linalool was dramatically higher (7.29-15.39%) in intercropped rose-scented
geranium in second harvest. As far as the quality indicator, C/G ratio, for
rose-scented geranium oil is concerned, it varied from 0.49 to 0.90 in present
study. Interestingly, C/G ratio was found to be better in intercropped rose-scented
geranium (0.71-0.86) than in sole (0.59) in first harvest. However, the situation
was somewhat different in second harvest where C/G ratio was noted to be higher
only in rose-scented geranium intercropped with cauliflower (0.90) than sole
crop (0.62). However, C/G ratio of rose-scented geranium intercropped with reddish
(0.60) was at par with sole in second harvest.

Resource use efficiency of intercrops: The resources (GEY, LER, ATR
and LUE %) values were indicated that intercrops better than monocrops of rose-scented
geranium (Table 7). The yield of different intercrops can
not be compared directly either among themselves, or with oil yield of rose-scented
geranium. Cauliflower intercrops gave maximum GEY (56%), followed by cabbage
intercrop (49%) over sole crop.

Table 7:

Variation in geranium equivalent yield (GEY) and resource
use efficiency (LER, ATER and LUE %) of different intercropping system (Average
of two cropping years)

Values in a column fallowed by the same letter within one
column are not significantly different at p = 0.0

The LERs were calculated for all combinations of intercropping. All intercrops
gave LERs greater than 1.0. The largest LER (1.54) was obtained from the intercrop
with cabbage followed by that with cauliflower. Area time equivalent ratio (ATER)
of rose-scented geranium intercropping systems ranged from 0.7 to 0.8 over sole
crop in the both years. The maximum land use efficiency% (LUE %) was obtained
in cabbage (119%), followed by cauliflower (117%) intercrop.

DISCUSSION

This production system can improve income and establish new enterprises in the region. Intercropping of high value aromatic crops in existing cropping systems produced higher agronomic efficiency of crop.

The plant canopy and leaf: stem ratio was lower than that of sole geranium
at the first harvest, probably due to competition of light, space, nutrition
and other resources by intercrops at the first harvest. A similar observation
was found in rose-scented geranium intercrops with fodder (Verma
et al., 2009), corn mint (Mentha arvensis L.) (Rajeswara
Rao, 2002) and Java citronella (Cymbopogon winterianus jowitt.) (Prakasa
Rao et al., 1988). But plant height was not significantly influenced
by intercrops at both harvests. Plant height of citronella (Cymbopogon winterianus
jowitt.) was also not affected when intercrops with mint species (Kothari
et al., 1987; Singh and Shivraj, 1998; Singh
et al., 1998b).

The results indicated that vegetables intercrop provided additional yield of
vegetables. Nevertheless, there is some loss of rose-scented geranium yield
(herb and oil yield) from first harvest if rose-scented geranium is intercropped
with vegetables. Vegetable pea and radish were showed more competition than
other vegetable intercrop at the first harvest of rose-scented geranium. Vegetable
pea and radish, fast growing and quickly covering inter-and intra-row spaces
restricted growth and plant canopy of rose-scented geranium. Biomass and oil
yield loses of rose-scented geranium was reported in intercrop with cow pea
and black gram (Prakasa Rao et al., 1984) and
green gram (Prakasa Rao et al., 1986). Similar
results were reported in other aromatic grass like vetiver (Vetiveria zizanioides
(Linn)), palmalrosa (Cymbopogon martini Roxb.), when intercropped with
pulses and vegetables decreased yield (Rajeswara Rao, 2002;
Rajeswara Rao et al., 1993; Prakasa
Rao et al., 1994; Singh et al., 1998a).
Since the yield of rose -scented geranium was affected at first harvest by intercropping
with vegetables, the additional vegetables yields and higher selling price of
vegetables could influenced the geranium equivalent yield (GEY). At second harvest
yield of rose-scented geranium was significantly improved in all intercrops
treatments except radish intercrop. A maximum increase was obtained in vegetable
pea intercrop followed by cabbage intercrop. Among all the treatments, vegetable
pea thus proved to be the most suitable intercrop with rose-scented geranium.
This may be due to the chemical and biological changes of the soil and the availability
of nitrogen by the legumes crops (Verma et al., 2009)
to rose-scented geranium at second harvest since vegetable pea, cabbage and
cauliflower are less competitive and complete their life cycle much earlier
than the rose-scented geranium, providing enough time to recover the competitive
experiences and to grow resulting in more yield than the sole geranium. A similar
observation was found in rose-scented geranium intercrop with cornmint (Rajeswara
Rao, 2002; Singh and Ram, 1991; Singh
et al., 1990).

It is imperative to mention here that the geranium oil possesses C/G ratio
equivalent to one is considered as the oil with best odour quality and hence,
preferred by industry (Southwell et al., 1995).
C/G ratio in rose-scented geranium is also influenced by date of planting, post
harvest storage and temperature (Doimo et al., 1999;
Ram et al., 2005; Verma et
al., 2010). However, present study showed that C/G ratio in rose-scented
geranium is also influenced significantly by growing geranium with vegetables
as intercrops. Finally, it can be conclude that quality of geranium oil can
be good by introducing vegetables as intercrops.

All the intercrops proved more efficient in utilizing resources and showed higher values of LER, ATER and LUE % than sole. The sustainability of any intercrops like cabbage, cauliflower, vegetable pea and radish will improve economics, equity and opportunities for producer.

ACKNOWLEDGMENTS

The author thanks to Director, CIMAP, Lucknow and CSIR, New Delhi, India for providing facilities and encouragement.